1. Field of the Invention
The present invention relates to zirconia fine particles, which are excellent in dispersibility and stability over a wide range of pH of a dispersion solution because the surface is coated with antimony pentoxide or silica, a dispersion sol of the fine particles and a method for producing the same. In addition, the present invention relates to a substrate with a hard coat film comprised with a substrate and a hard coat film formed on the substrate and excellent in adhesiveness with the substrate, abrasion resistance, scratch strength, pencil hardness and the like, in which the refractive indices of the substrate and a transparent film may be adjusted to the same degree and thus no interference fringes occurs, because the substrate with the hardcoat film may be readily adjusted in refractive index in a predetermined range and contains composite oxide particles excellent in dispersibility and stability, and a coating solution used for forming the hard coat film.
2. Description of the Related Art
In order to improve abrasion resistance on the surface of a substrate such as glass, a plastic sheet, a plastic lens, a resin film, a display front panel and the like, it is known that a hard coat film is formed on the surface of the substrate and it has been conducted that an organic resin film or an inorganic film is formed on the surface of glass, plastics and the like as such a hard coat film. In addition, it has been conducted that resin particles or inorganic particles such as silica and the like are blended in the organic resin film or inorganic film to further increase abrasion resistance.
For example, there is known a hard coat film blended therein with inorganic oxide particles such as silica particles, zirconia, ITO, ATO, antimony pentoxide particles and the like, mixed particles thereof, chain particles thereof or the like.
In addition, colloidal particles such as silica, alumina, titania, zirconia, zinc oxide, antimony pentoxide, cerium oxide, tin oxide, silica-alumina, silica-zirconia and the like are used as an optical material by blending the particles with a film and the like to adjust a refractive index. For example, silica is used as a low refractive index material, alumina as a middle refractive index material and titania, zirconia and the like as a high refractive index material.
Although titania particles have a high refractive index, they had a problem with dispersion resistance, as well as light resistance, weather resistance and the like due to the photocatalytic activity depending on the usage and application. For this reason, it has been conducted that dispersion stability as well as light resistance, weather resistance and the like are improved by forming a composite component of other components, for example, a silica component and the like. However, in addition to the fact that some of composite components reduce refractive index, it is difficult to completely suppress the photocatalytic activity, and thus there was a case where light resistance, weather resistance and the like became insufficient (Patent Document 1: refer to Japanese Patent Laid-Open Publication No. H08-48940).
On the other hand, although zirconia particles have substantially no photocatalytic activity and are excellent in light resistance, weather resistance and the like, it was difficult to obtain a zirconia sol in the colloidal range having a uniform particle size distribution and excellent in stability.
Consequently, the applicant of this application has disclosed that a zirconia sol having a uniform particle size distribution and excellent in stability is obtained by preparing a zirconia gel in the presence of a particle growth regulator and performing the hydrothermal treatment (Patent Document 2: refer to Japanese Patent Laid-Open Publication No. 2006-143535).